...No longer exists? Did they forget how to make it or did it turn into something else entirely?
Scotch became socially trendy enough by end of the 19th century for the English distilleries to all slowly fall out of business, and all were closed by iirc 1905. The
exotic Scotland bug of Walter Scott was too appealing for the market, and everybody else gave up. The same happened to the Irish ones when Ireland became independent - the biggest market (the UK) suddenly dried up, and in combination with prohibition in the US, there were few-to-no Irish distilleries remaining either. I think by the 1970s, Jameson was the only existing distiller in Ireland, and even they weren't quite the brand we recognise today and took a while to be recognised as a bottler in its own right. Effectively all of the modern Irish distilleries are revivals, which is where Auchentoshan becomes valuable, as it's an Irish-style distillery in Scotland that did survive, so serves as a window into the past. There is a distinct 'Irish' flavour of Whisky, but it exists as a conceptual touchstone rather than a living tradition, though of course over time this will change. Redbreast is the most impressive example of a modern Irish whisky and if anyone can afford it, the cask strength 12 is divine. The regular 12 is good enough by any measure.
There are a few recent startups in England, motivated by the increasing price boom in whisky since the Scotch recession in the 1980s, but it's pretty hard to start up a distillery focusing on long-term maturation of stock, as you will potentially struggle to make a strong income for decades. A lot of them prop up their enterprise by making gin and other things on the side since the margins are better and more readily-coming. I don't think it's worth mentioning distilleries of 'potential' until they begin releasing product (in the UK it must be matured for 3 years), but ones in England that have been producing and releasing for long enough to be.... 'something', I suppose are St George's Distillery and Cotswolds Distillery. Penderyn is the only notable Welsh one. Scotland has a bunch, the most interesting being Daftmill and maybe Ardnahoe, but the former at least is too expensive at the moment.
In general Scotch/UK style distilleries seem really hard to keep open, since they're very exposed to shifting market trends combined with economic fluctuations and if they can no longer rely on their reserves, or there is a decline in quality, they can't magic up stock without waiting for long periods of time during which they could go bankrupt. Scotch seems to benefit more than any other cask spirit from long maturations in particular, and depending on distiller the difference between a 9 and 18 can be immense. If they reach a point where they can coast on name-recognition alone that is nice, but the rest find it a lot less easy to get by. With blends becoming less popular, some of the less renowned bulk distillers have been slowly mothballed over time as well, and that is another market pressure that can affect producers (nowadays a lot of distillers for blends are also releasing their own single malts, something that was never done in the past, due to demand). A lot of Scotch distilleries have disappeared over time for economic reasons rather than the quality of their product (the worst being the 1980s after vodka had become trendy, when a lot of big names - both blends and single malts - disappeared, along with their traditions). Sorry for sperging, this was probably too long for such a straightforward question but I think the context might be useful.
